Metal plate chip resistors composed of a resistive metal element in the form of an alloy plate and electrode films formed over the ends of the resistive element are conventionally used for detection of electrical current or other purposes. For such purposes, the resistance of the chip resistors is set at a relatively low level, such as from several milliohms to one ohm. There have been demands for higher accuracy and lower resistance of metal plate chip resistors, and Patent Publication 1 discloses an apparatus intended to meet such demands.
Patent Publication 1 discloses an apparatus for adjusting the resistance of a metal plate resistor including: probes to be contacted with electrodes formed over the ends of a metal plate for measuring the resistance of the metal plate; a grind stone disc for notching the metal plate to adjust the resistance; a rotary mechanism and a transfer mechanism for rotating and advancing the grind stone disc; means for injecting a gas against the metal plate during the notching process; and an instantaneous adjustment-stop mechanism for stopping the notching by detaching the grind stone disc from the metal plate when the metal plate is adjusted to have a desired resistance.
In this apparatus for adjusting the resistance, the grind stone disc is alternately rotated in forward and reverse directions for notching the metal plate.
Another trimming apparatus for metal plate resistors is disclosed in Patent Publication 2, which includes a pulse excited laser apparatus; an irradiating optical part which focuses the laser beam generated by the pulse excited laser apparatus and irradiates a resistive metal element for cutting the same; irradiation positioning means for positioning the irradiation of laser beam from the irradiating optical part; measuring means for measuring the resistance of the resistive metal element during cutting; and means for preventing adhesion of debris which prevents, at a site where the resistive metal element is supported, adhesion of debris produced by cutting the resistive metal element.
Patent Publication 3 discloses in paragraphs [0036] and [0037] a method for giving a desired resistance to a jointed body (a metal plate joined with electrodes), which has been cut into a predetermined length, by removing part of the side or top surface portion of the jointed body by a sand blasting machine or various cutting machines, such as a laser machining device, while the resistance is monitored.
Patent Publication 1: JP-3873819-B
Patent Publication 2: JP-3525815-B
Patent Publication 3: JP-2007-103976-A